During the First World War the Italian Army built on the Kolovrat range an extensive system of the third line of defence, called “linea d’armata”, a part of which is now arranged as the outdoor museum. It presents commanders and observation posts, machine-gun and gun positions, caves and networks of trenches. A visit to these positions is of special interest thanks to various details, such as spiral stairs in one of the caves, and also due to partly original materials which were used in the wartime. The outdoor museum Kolovrat is a trans-border museum which continues on the Italian side, too.